1. Field of the Invention
The present invention relates to a posture recognition apparatus and an autonomous robot which recognizes instructions which a person issues, by capturing images and recognizing the posture of the person.
2. Background Art
Conventionally, autonomous robots that recognize instructions to themselves by means of voice recognition of vocal commands uttered by a person, and initiate movement, are known. These have the characteristic in the case of instructing the autonomous robot, of enabling the person instructing to give instructions without employing special apparatus.
However, the by-voice instruction system has the problem of requiring time for recognition because the voice recognition rate decreases in places where there is a lot of noise. Furthermore, with the voice recognition system, in order to increase the rate of recognition it is necessary to pre-register the voice of the person who utters the voice command and so the construction of the system becomes complicated.
In order to solve this kind of problem, an instruction recognition method employing image information is being tested. For example, the Gesture Recognition System described in Japanese Unexamined Patent Application First Publication No. Hei 8-315154 (hereafter referred to as prior art 1) is known. This system detects the hand of the person issuing the instruction by first employing the obtained image captured by a single camera and a hand template, and then carrying out the process of obtaining a normalized correlation with the angle of directionality of the localized image. The movement of the detected hand is then tracked in directions X and Y (relative position directions), a gesture signal corresponding to the position in space generated, and the machine is then controlled based on this gesture signal.
Also, the autonomous robot described in the Japanese Unexamined Patent Application First Publication No. 2000-326274 (hereafter referred to as prior art 2) is known. This autonomous robot detects persons from an image obtained with a stereo camera and controls its own movements corresponding to the various inputs of; detection of the direction of the sound source, voice recognition, touch sensor, ultrasonic sensor, of the movement of this detected person.
If these techniques are employed, they can be used as a human-robot interface in which the robot initiates its next movement by recognizing persons in the surroundings and recognizing the instructions issued by these persons.
However, in the method of carrying out detection of the hand, based on correlation with templates as in prior art 1, a plurality of templates are pre-stored internally for each hand size or shape, and detection of the hand is carried out by matching an image of a captured hand with a template. Therefore, along with having to store internally an enormous data volume of templates, and because of the enormous amount of calculation time that the matching process would necessitate, conditions are not suitable for carrying out real-time processing. With the method employing templates, because the setting of templates that can correspond to arbitrary image input is not easy, the operation mode is limited such as with the operation of a television set or the like. Furthermore, because the autonomous robot moves around freely, and because the background of the obtained image and the distance to the person giving the instructions cannot be fixed, posture recognition processing by means of template matching cannot be applied.
In the method as in prior art 2 in which a particular person is detected and identified, the object is to recognize an isolated person within a predetermined target measurement area. Therefore, in the case in which a plurality of persons are present within the obtained image, self action cannot be decided.
An object of the present invention is to provide a posture recognition apparatus which, even when installed on a moving body which can move freely, can carry out highly reliable posture recognition at high speed, and an autonomous robot that initiates movement based on the posture recognition result.